Not Applicable
Not Applicable
1. Field of the Invention
The present invention relates to a pet door which is remotely opened by a user. In particular, the present invention relates to a pet door which uses a vertical opening mechanism to lift the door into the open position in response to a signal from a portable transmitter controlled by the user.
2. Description of the Related Art
The related art has shown various types of pet door mechanisms. Illustrative are U.S. Pat. No. 4,322,913 to Himmer; U.S. Pat. No. 5,072,544 to Breck, Jr.; U.S. Pat. No. 5,177,900 to Solowiej and U.S. Pat. No. 5,651,331 to Cleri, Jr.
Himmer describes a vertically sliding pet door. The operating mechanism is a motor which rotates a shaft having a flexible line which is connected to the top of the door. The door is activated when the pet steps on either of a pair of floor mounted pressure pads mounted adjacent the inside and outside of the door, respectively.
Breck, Jr. shows an electrically powered pet door. The opening mechanism is a rotational and transitional drive unit which decreases the length of a line attached to the door to lift the door. The door is opened when the pet depresses a pedal plate on either the outside or.inside of the door.
Solowiej shows an automatic, vertical pet door for mounting between studs of a wall. The opening mechanism is an arm which rotates upward in an arc and moves in a slot in the door to open the door. The structure of the arm of the opening mechanism prevents the door from being lifted when the motor is not activated. The door is opened when the pet, having a transmitter unit on its collar, comes within range of a detector mounted on the framework of the door. The transmitter signal can be of any of infrared, ultraviolet, ultrasound or electromagnetic transmissions. The door stays open a predetermined amount of time as determined by a delay mechanism. If the pet is still within range of the detector, when the door begins to close, the door will reopen which prevents the pet from being hurt by the door.
Cleri, Jr. discloses a vertically or horizontally opening emergency pet door which is adapted to be mounted between studs in a building. The opening mechanism is a motor having a cord which is attached to the top of the door. As the motor rotates, the door is opened. The door has a speaker with a recorder to call the pet to the door. The door also has a smoke detector unit which activates the opening mechanism when smoke is detected.
Also of interest is U.S. Pat. No. 3,918,201 to Graziano which describes a horizontally sliding door in which the opening mechanism is a threaded rod rotated by a motor having a nut mounted thereon and attached to the door.
Only of minimal interest is U.S. Pat. No. 5,422,552 to Parisi which describes an automated actuator for use with sliding doors which ceases the sliding movement of the door when the door meets resistance and re-tests for the resistance to determine whether the door should continue along the intended path.
There remains the need for a pet door unit using a screw drive to vertically open the door in response to a signal from a portable transmitter controlled by the user.
The present invention is a pet door unit which opens in response to a signal from a portable transmitter. The pet door unit has a housing which is adapted to be mounted between a pair of standard studs in a structure. The door is mounted such as to open vertically by a opening mechanism. The opening mechanism includes a motor having a screw drive and a carriage movably mounted on the screw drive. The carriage is also connected to the top of the door such that as the screw drive rotates, the carriage moves along the screw drive and opens and closes the door. The screw drive prevents the door from being forced opened when the unit is not activated. The opening mechanism has a receiver which receives a signal from the portable transmitter to open the door. The portable transmitter enables the user to open the door from a distance either from inside or outside the structure.